Tissue-removing catheter including angular displacement sensor

ABSTRACT

A tissue-removing catheter for removing tissue from a body lumen includes a tissue-removing element. The tissue-removing element may be coupled to a first longitudinal portion of the catheter body. An angular-displacement sensor may be coupled to the catheter body for detecting an angular displacement of at least the first longitudinal portion of the catheter body relative to the rotational axis when the first longitudinal body portion is rotated about the rotational axis. The tissue-removing element may be rotatable about a rotational axis to adjust an angular tissue-removing position of the tissue-removing element relative to the body lumen when the catheter body is inserted in the body lumen. An angular-displacement sensor may be generally adjacent the tissue-removing element for detecting an angular displacement of the tissue-removing element relative to the body lumen when the tissue-removing element is rotated about the rotational axis.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a tissue-removing catheterincluding an angular displacement sensor.

BACKGROUND OF THE DISCLOSURE

Debulking or tissue-removing catheters are used to remove unwantedtissue from the body. As an example, atherectomy catheters are used toremove material from a blood vessel to open the blood vessel and improveblood flow through the vessel.

SUMMARY OF THE DISCLOSURE

In one aspect, a tissue-removing catheter for removing tissue from abody lumen includes a tissue-removing element. The tissue-removingelement may be coupled to a first longitudinal portion of the catheterbody. An angular-displacement sensor may be coupled to the catheter bodyfor detecting an angular displacement of at least the first longitudinalportion of the catheter body relative to the rotational axis when thefirst longitudinal body portion is rotated about the rotational axis.

In another aspect, the tissue-removing element may be rotatable about arotational axis to adjust an angular tissue-removing position of thetissue-removing element relative to the body lumen when the catheterbody is inserted in the body lumen. The angular-displacement sensor maybe generally adjacent the tissue-removing element for detecting anangular displacement of the tissue-removing element relative to the bodylumen when the tissue-removing element is rotated about the rotationalaxis.

Other features will be in part apparent and in part pointed outhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a catheter body and a schematicrepresentation of a handle, each of which are part of a catheter;

FIG. 2 is an enlarged fragmentary cross section of the catheter body,illustrating a tissue-removing element in a deployed position;

FIG. 3 is an enlarged fragmentary side elevation of the catheter body;

FIG. 4 is an enlarged fragmentary side elevation of the catheter bodyreceived in a blood vessel shown in section;

FIG. 5 is a schematic cross section of the catheter body received in ablood vessel taken in the plane defined by the line 5-5 in FIG. 4;

FIG. 6 is an enlarged fragmentary section taken in the plane defined bythe line 6-6 in FIG. 8;

FIG. 7 is similar to FIG. 5, except illustrating a change in an angulartissue-removing position of the tissue-removing element of the catheterbody;

FIG. 8 is an enlarged fragmentary bottom elevation of the catheter body;

FIG. 9 is an electrical diagram of electrical components of the catheteraccording to one or more embodiments;

FIG. 10 is an enlarged schematic of the handle in FIG. 1;

FIG. 11 is an electrical diagram of electrical components of thecatheter according to one or more embodiments;

FIG. 12 is an enlarged fragmentary bottom elevation of the catheterbody, including portions broken away to show underlying components;

FIG. 13 is a block diagram illustrating a control circuit and componentsin communication with the control circuit according to the embodimentillustrated in FIG. 9;

FIG. 14 is a block diagram illustrating a control circuit and componentsin communication with the control circuit according to the embodimentillustrated in FIG. 11;

FIG. 15 is a schematic of the catheter body shown in a linearconfiguration;

FIG. 16 is a block diagram illustrating a control circuit and componentsin communication with the control circuit according to one or moreembodiments; and

FIG. 17 is an enlarged schematic of one embodiment of a handle for usewith the embodiment illustrated in FIG. 16.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

Embodiments of a tissue-removing catheter having improved angulartissue-removing positioning within a body lumen for removing tissue fromthe body lumen are disclosed. In particular, the illustrated catheterembodiments are particularly suitable for removing (i.e., excising)plaque tissue from a blood vessel (e.g., peripheral arterial orperipheral venous wall). Features of the disclosed embodiments, however,may also be suitable for treating chronic total occlusion (CTO) of bloodvessels, particularly peripheral arteries, and stenoses of other bodylumens and other hyperplastic and neoplastic conditions in other bodylumens, such as the ureter, the biliary duct, respiratory passages, thepancreatic duct, the lymphatic duct, and the like. Neoplastic cellgrowth will often occur as a result of a tumor surrounding and intrudinginto a body lumen. Removal of such material can thus be beneficial tomaintain patency of the body lumen. While the remaining discussion isdirected toward catheters for removing tissue from, and penetratingocclusions in, blood vessels (e.g., atheromatous or thrombotic occlusivematerial in an artery, or other occlusions in veins), it will beappreciated that the teachings of the present disclosure apply equallyto other types of tissue-removing catheters, including, but not limitedto, catheters for penetrating and/or removing tissue from a variety ofocclusive, stenotic, or hyperplastic material in a variety of bodylumens.

Referring to FIG. 1, a tissue-removing catheter, in accordance with oneor more embodiments of the present disclosure, is generally indicated atreference numeral 10. The catheter 10 comprises an elongate catheterbody, generally indicated at 12, having opposite proximal and distalends 12 a, 12 b, respectively, and a longitudinal axis A1 (FIG. 3)extending between the proximal and distal ends. A handle or controlunit, generally indicated at 14, is attachable to the proximal end 21 aof the catheter body 12, although the handle may be fixedly attached tothe catheter body in other embodiments. A tissue-removing element,generally indicated at 16, generally adjacent the distal end 12 b of thecatheter body 12, is configured to remove (e.g., cut) tissue from thebody lumen and direct the removed tissue into a tissue container 17.

Referring to FIG. 2, in the illustrated embodiment, the tissue-removingelement 16 comprises a rotatable cutting element that is rotatable abouta rotation axis RA1 for cutting tissue. The illustrated cutting element16 has a cutting edge 18 facing distally, although in other embodimentsthe cutting edge may face proximally, and a cup-shaped surface 20 fordirecting removed tissue distally into the tissue container 17 of thecatheter body 12. In other embodiments, the tissue-removing element mayhave other configurations for cutting tissue, or may be configured toremove tissue in other ways. For example, the tissue-removing elementmay be configured to ablate tissue, or abrade tissue, or otherwiseremove tissue from the body lumen. Moreover, the tissue-removing elementmay not be rotatable relative to the catheter body.

Referring still to FIG. 2, a tissue-removing driveshaft 26 isoperatively connected to a stem 28 of the tissue-removing element 16(e.g., fixedly secured thereto) for imparting rotation to thetissue-removing element. The tissue-removing driveshaft 26 (e.g., acoiled driveshaft) extends through the catheter body 12 and isoperatively connectable to an electric driveshaft motor 30 (FIG. 10), orother prime mover, in the handle 14 for driving rotation of thedriveshaft, and in turn, driving rotation of the tissue-removing element16, relative to the catheter body. The driveshaft motor 30 iselectrically connected to a power source 21 (FIG. 10) in the handle 14.In the illustrated embodiment, the driveshaft 26 is movablelongitudinally within the catheter body 12 to impart longitudinalmovement of the tissue-removing element 16 relative to the catheterbody. Longitudinal movement of the tissue-removing element 16 actuatesdeployment and storage of the tissue-removing element relative to atissue-removing housing 34, which is part of the catheter body 12. Thetissue-removing housing 34 (e.g., a proximal end portion thereof) pivotsabout a pivot axis PA (FIG. 3) that is generally transverse to thelongitudinal axis A1 of the catheter body. A distal portion of thehousing 34 forms the tissue container 17, although the housing and thetissue collection chamber may be formed separately.

The tissue-removing element 16 is movable between a stored position (notshown) and a deployed position (FIGS. 1 and 2). In the stored position,the tissue-removing element 16 is received in the housing 34 and is notexposed through a window or side opening 38 of the housing. To deploythe tissue-removing element 16, the driveshaft 26 is moved proximallyrelative to the catheter body 12, such as by moving a lever or otheractuator 40 (FIG. 1) on the handle 14 that is operatively connected tothe driveshaft, to impart proximal movement of the tissue-removingelement 16 relative to the housing 34. Referring to FIG. 2, as thetissue-removing element 16 moves proximally, the tissue-removingelement, which acts as a cam, engages and moves longitudinally along aninternal cam follower 42 of the housing 34, causing the housing to pivotabout the pivot axis PA (FIG. 4) and the tissue-removing element toextend partially out of the window 38. A switch 43 (FIG. 11) may becoupled to the actuator 40 such that the driveshaft motor 30 activates(i.e., turns on) to impart rotation to the driveshaft 26 when thetissue-removing element 16 is deployed. To return the tissue-removingelement 16 to its stored, non-deployed position, the driveshaft 26 ismoved distally, such as by moving the actuator 40 distally, to impartdistal movement of the tissue-removing element 16 along the cam follower42. Distal movement of the tissue-removing element 16 causes the housing34 to pivot or deflect back about the pivot axis PA so that thetissue-removing element is received in the housing 34 and does notextend outside the window 38. When the tissue-removing element 16 is inits stored position, the driveshaft motor 30 is deactivated (i.e.,turned off). It is understood that a catheter 10 constructed accordingto the principles of the present disclosure may not include a deploymentmechanism (e.g., the tissue-removing element or other functional elementmay always be deployed or may remain within the catheter body).

Referring to FIG. 3, the catheter body 12 includes a first (distal)longitudinal body portion 46 defining a distal portion of the catheterbody, and a second (proximal) longitudinal body portion 48 that isproximal of the first (distal) longitudinal body portion. In theillustrated embodiment, the second (proximal) longitudinal body portion48 extends from adjacent a proximal end of the first (distal)longitudinal body portion 46 toward the proximal end 12 a of thecatheter body 12. As explained in more detail below, the first (distal)longitudinal body portion 46 is selectively rotatable along its lengthand relative to the second (proximal) longitudinal body portion 48 abouta second rotational axis A2 (FIG. 5). In particular, the first (distal)longitudinal body portion 46 is operatively connected to anangular-positioning mechanism 60 for imparting rotation of the first(distal) longitudinal body portion along its length and relative to thesecond (proximal) longitudinal body portion 48. The first and second(proximal) longitudinal body portions 46, 48, respectively, are suitablyflexible for navigating the catheter body 12 through tortuous pathswithin the body lumen BL. The first (distal) longitudinal body portion46 may comprise a torque tube (e.g., a coiled member) for transmittingtorque from its proximal end toward its distal end, as explained in moredetail below. In particular, the torque tube of the first longitudinalportion 46 may be formed from coiled stainless steel or other materialsand constructions. The second (proximal) longitudinal body portion 48may also comprise a torque tube, although for reasons explained in moredetail below, the second (proximal) longitudinal body portion may notinclude a torque tube as it may not be necessary for the second(proximal) longitudinal body portion to be capable of effectivelytransmitting torque from its proximal end toward its distal end.

Referring still to FIG. 3, the catheter 10 comprises an appositionmember, generally indicated at 52, that is configured to apply anapposition force in a generally radial direction relative to alongitudinal axis A1 of the catheter body 12 to direct thetissue-removing element 16 toward a peripheral (or circumferential)portion of the body lumen when the catheter is inserted in the bodylumen BL defined by the blood vessel V. In the illustrated embodiment,the apposition member 52 comprises a jogged portion of the first(distal) longitudinal body portion 46 that is biased or preformed in ajogged or curved configuration. In other embodiments, the appositionmember 52 may be of other constructions for directing thetissue-removing element 16 toward a peripheral portion of the body lumenBL. For example, in other embodiments the apposition member may comprisean inflatable member secured adjacent the tissue-removing element 16 ona side of the housing 34 that is opposite the window 38. In otherembodiments, the housing 34 may function as the apposition member,whereby pivoting of the housing directs the tissue-removing element 16toward a peripheral or circumferential portion of the body lumen. Theapposition member may be of other constructions.

As can be seen in FIG. 4, when the catheter 10 is inserted in the bodylumen BL, the apposition member 52 engages a peripheral portion of thebody lumen BL defined by the blood vessel V to maintain thetissue-removing element 16 and/or the window 38 (FIG. 2) in appositionwith an opposite peripheral portion of the body lumen that is generallydiametrically opposite (e.g., 180 degrees from) the peripheral portionengaged by the apposition member. This angular position of thetissue-removing element 16 relative to the longitudinal axis A2 of thebody lumen BL is referred to herein as the “angular tissue-removingposition.” In the schematic of FIG. 5, the angular position of thetissue-removing element 16 is offset 0 degrees from a reference plane RPpassing through the body lumen BL. In general, the angulartissue-removing position of a tissue-removing element 16 is about 180degrees offset from the location of the force applied to the body lumenBL by the apposition member.

Referring to FIG. 6, the angular-positioning mechanism 60 allows theuser to rotate the apposition member 52 (and this the tissue-removingelement 16) within the body lumen BL to adjust the angulartissue-removing position of the tissue-removing element relative to thelongitudinal axis A2 of the body lumen, without manually rotating ortorqueing the second (proximal) longitudinal body portion 48 of thecatheter body. In particular, the angular-positioning mechanism 60 isoperatively connected to the apposition member 52 and configured torotate the apposition member relative to the second (proximal)longitudinal body portion 48 of the catheter body 12 about therotational axis A2 to adjust the angular tissue-removing position of thetissue-removing element relative to the longitudinal axis A2 of the bodylumen BL when the catheter 10 is inserted in the body lumen. In theillustrated embodiment, the angular-positioning mechanism 60 includes aprime mover, such as an electric motor, located between the first(distal) and second (proximal) longitudinal body portions 46, 48 andelectrically connectable to a power source, such as the same powersource 21 electrically connectable to the driveshaft motor 30, or adifferent power source. In particular, the illustratedangular-positioning motor 60 is a pass through electric motor includinga rotor 63, a stator 64, and a hollow output shaft 65 connected to thefirst (distal) longitudinal body portion 46. The angular-positioningmotor 60 has an opening 68 that is coaxial with lumens 70, 72 defined bythe respective first (distal) and second (proximal) longitudinal bodyportions 46, 48. The driveshaft 26 passes through the opening 68 in theangular-positioning motor 60 and through the lumens 70, 72. Theangular-positioning motor 60 may be other types of electric motors, orother types of prime movers. In other embodiments, theangular-positioning mechanism 60 may be located elsewhere on thecatheter 10, such as another location on the catheter body 12 or in thehandle 14, for rotating at least the first (distal) longitudinal bodyportion 46 about its length.

Referring to FIG. 7, the illustrated apposition member 52 functions asan eccentric because it is not coaxial with (i.e., is off-center from)the rotational axis A2 of the angular-positioning mechanism 60. Ineffect, rotating the apposition member 52 about the rotational axis A2adjusts the angular tissue-removing position relative to the body lumenBL and allows the user to direct the tissue-removing element 16 toward adifferent peripheral portion of the body lumen. For example, in theschematic illustration of FIG. 7, the apposition member 52 is rotatedrelative to the axis A2 of the body lumen BL so that the angulartissue-removing position of the tissue-removing element 16 (shown insolid lines) is offset an angle α, measuring about 60 degrees in theclockwise direction, from a reference tissue-removing position (shown inbroken lines) of the tissue-removing element.

Referring to FIG. 8, the angular-positioning motor 60 is electricallyconnectable to the power source 21 via one or more electrical conductors74, such as wires or flex circuits, running along the catheter body 12.In the illustrated embodiment, the electrical conductors 74 are receivedin a wire lumen 78 that is separate and free from communication with thedriveshaft lumens 70, 72 of the catheter body 12. In other embodiments,the electrical conductors may be received in the driveshaft lumens 70,72. The angular-positioning motor 60 may be powered in other ways,including a local battery or in other ways, whereby the electricalconductors may be omitted.

An electrical schematic including the power source 21, the driveshaftmotor 30, and the angular-positioning motor 60 is shown in FIG. 9. Thecatheter 10 includes a power switch 79 for selectively connecting thepower source 21 to respective switches 43, 80 for the driveshaft motor30 and the angular-positioning motor 60. In this illustrated embodiment,an actuator 81 (e.g., toggle, as illustrated, or a lever or slide orbutton), as shown in FIG. 10, is provided on the handle 14 toselectively actuate the switch 79. The switch 80 for selectivelyconnecting the angular-positioning motor 60 to the electrical powersource 21 to operate the angular-positioning motor may be a mechanicalswitch (as illustrated) or a solid-state switch or other types ofswitches. In this illustrated embodiment, an actuator 82 (e.g., toggle,as illustrated, or a lever or slide or button), as shown in FIG. 10, isprovided on the handle 14 to selectively actuate the switch 80. In theembodiment illustrated in FIG. 9, the switch 80 allows the user toselectively control the direction of rotation of the angular-positioningmotor 60 and the apposition member 52. As an example, the switch 80 maybe a double pole center off switch. When the actuator 82 is in the “off”position (i.e., neither rotational direction is selected), the terminalsets 1A, 1B, 2C, and 2D are open and the angular-positioning motor 60 isnot activated. To move the apposition member 52 in the clockwisedirection (and thus adjust the angular tissue-removing position of thetissue-removing element 16 in the body lumen BL), the user selects the“clockwise” direction on the actuator 82. For example, the user maydepress the right side of the illustrated toggle actuator 82, wherebythe terminals sets 1A and 2C are closed and the terminal sets 1B and 2Dare open. Electrical current flows through the closed terminal sets 1Aand 2D powers rotation of the angular-positioning motor 60 in theclockwise direction to rotate the apposition member 52 in the clockwisedirection. To move the apposition member 52 in the counterclockwisedirection (and thus adjust the angular tissue-removing position of thetissue-removing element 16 in the body lumen BL), the user selects the“counterclockwise” direction on the actuator 82. For example, the usermay depress the left side of the illustrated toggle actuator 82 toactuate closing of the terminals sets 1B and 2D, while the terminal sets1A and 2C are open. Electrical current flows through the closed terminalsets 1B and 2D powers the angular-positioning motor 60 in thecounterclockwise direction to rotate the apposition member in thecounterclockwise direction.

Referring still to FIG. 9, one or more pulse width modulators (PWM) 86are electrically connected to the angular-positioning motor 60 forregulating a duty cycle supplied to the angular-positioning motor fromthe power source 21. In this example, the electrical current is receivedfrom the same power source 21 as the driveshaft motor 30. The modulators86 effectively regulate the duty cycle supplied to theangular-positioning motor 60 to regulate the rotational speed of themotor in either direction. It is envisioned that the one or moremodulators 86 will regulate the speed of the angular-positioning motor60 to substantially less than that of the driveshaft 26 (e.g., fromabout 1 rpm to about 60 rpm). The one or more modulators 86 may bereceived in the handle 14 or in the catheter body 12. It is understoodthat catheter may not include such a pulse with modulator 86 in otherembodiments.

The switch 80 may be of other types of switches. For example, in theembodiment illustrated in FIG. 11, the switch 80′ is a single pole,single throw switch, whereby when the switch is on (i.e., the circuitpath is closed) power is supplied to the angular-positioning motor 60(the angular-positioning motor is on and operating), and when the switchis off (i.e., the circuit path is open) power is interrupted to theangular-positioning motor (the angular-positioning motor is off andnon-operating). In this embodiment, the angular-positioning motor 60 isconfigured to rotate in only one-direction (e.g., clockwise).

As shown in FIG. 12 (and also shown in FIG. 2), the illustrated catheter10 includes an angular-displacement sensor 87 in addition to theangular-positioning mechanism 60. In other embodiments the catheter 10may include one of the angular-positioning mechanism 60 and theangular-displacement sensor 87, and not the other. Theangular-displacement sensor 87 is used for determining the angulartissue-removing position of the tissue-removing element 16 relative tolongitudinal axis A2 of the body lumen BL. In the illustratedembodiment, the angular-positioning mechanism 60 and theangular-displacement sensor 87 together allow the user to determine theangular tissue-removing position of the tissue-removing element in thebody lumen BL during treatment and adjust this angular position aselected magnitude and/or direction, without manually rotating ortorqueing the second (proximal) longitudinal end body portion 48 of thecatheter body 12.

Referring still to FIG. 12 (also shown in FIG. 2), theangular-displacement sensor 87 is associated with the first (distal)longitudinal end body portion 46 of the catheter body 12 and isconfigured to detect the angular displacement of the apposition member52 (and the angular tissue-removing position of the tissue-removingelement 16 relative to the longitudinal axis A2 of the body lumen BL).In the illustrated embodiment, the angular-displacement sensor 16 isfixedly secured to the housing 34, and more particularly, to the camfollower or ramp 42 within the housing. A bottom side of the ramp 42 hasa cutout or recess 88 (see FIG. 2) in which the angular-displacementsensor 87 is received. In the illustrated embodiment, theangular-displacement sensor 87 is a solid-state sensor, such as anintegrated circuit mounted on a circuit board 90. For example, in oneembodiment the angular-displacement sensor 87 may be a gyroscope. Theangular-displacement sensor 87 may be other types of sensors, other thana gyroscope. For example, the angular-displacement sensor 87 may be amagnetometric sensor, which is used to determine the angulartissue-removing position of the tissue-removing element 16 relative tothe magnetic fields of the earth. The angular-displacement sensor 87 maybe secured to the catheter body 12 at other locations for detecting theangular displacement of the apposition member 52 and the displacement ofthe angular tissue-removing position of the tissue-removing element 16.The catheter 10 includes one or more electrical conductors 92 (e.g.,wires) electrically connected to the angular-displacement sensor 87 andrunning along the catheter body 12 toward the proximal end 12 a of thebody. In particular, the electrical conductors 92 are received in a wirelumen 94 at the first (distal) longitudinal body portion 46 and in thewire lumen 78 at the second (proximal) longitudinal body portion 48. Thelumens 78, 94 are separate and free from communication with thedriveshaft lumens 70, 72. The electrical conductors 92 are electricallyconnectable to a control circuit 94 and the power source 21. The controlcircuit 94 may be provided in the handle 14, as illustrated, or thecontrol circuit may be provided in the catheter body 12, such as on thesame circuit board 91 as the angular-displacement sensor 87.

Referring to FIG. 13, in the illustrated embodiment, the control circuit94 is configured (e.g., programmed) to receive electrical signals fromthe angular-displacement sensor 87, compute the angular displacement ofthe tissue-removing element 16, and communicate the magnitude anddirection of the displacement to the user via a user interface 96. Inthe illustrated embodiment, the user interface 96 comprises a display(e.g., an LCD screen or other electronic display screen) on the handle14 (See FIGS. 1 and 10). As explained in more detail below whendiscussing an exemplary method of use, the control circuit 94 isconfigured (e.g., programmed) to compute the angular displacement of thetissue-removing element 16 (and/or the angular displacement of theapposition member 52) relative to a reference angular tissue-removingposition based on the electrical signals received from theangular-displacement sensor 87. The control circuit 94 then displays thecomputed angular displacement on the display 96 for the user, such asillustrated in FIG. 10. Thus, as the user actuates operation of theangular-positioning motor 60, the user can observe the displayed angulardisplacement on the display 96 as feedback to make a determination as tothe contemporaneous angular tissue-removing position of thetissue-removing element 16 in the body lumen BL. As also shown in FIG.13, the power source 21 and the pulse width modulator(s) 86 may be inelectrical communication with the control circuit 94. The controlcircuit monitors the amount of electrical power being drawn byangular-positioning motor 60 and/or the driveshaft motor 30. Based onthe amount of electrical power being supplied to one or both of themotors 60, 30, the control circuit 94 can adjust the duty cycle suppliedto the angular-positioning motor 60, through communication with thepulse width modulator(s) 86, to ensure that the motor rotates at adesired speed.

FIG. 14 illustrates an electrical diagram for the embodiment illustratedin FIG. 11. As shown in FIG. 14, the control circuit 94 is in electricalcommunication with the sensor 87 and the display 96 in the manner setforth above with respect to FIG. 13. However, in this example thecatheter 10 does not include a pulse width modulator, so the controlcircuit is not in communication with the power source 21 or theangular-positioning motor 60 for regulating power supplied to the motor.

In an exemplary method of using the illustrated catheter 10, the distalend 12 b of the catheter body 12 may be inserted into the body lumen BLdefined by the blood vessel V, such as a peripheral artery of apatient's leg, and traversed through the body lumen to a target site.For example, the target site may be a stenotic lesion T (i.e., build-upof plaque) in the vessel V. Upon reaching the target site T in thevessel V and prior to deploying the tissue-removing element 16, thecontrol circuit 94 may compute the contemporaneous angulartissue-removing position of the tissue-removing element 16 and store thecomputed angular position in the memory as a reference angulartissue-removing position. In the illustrated example, the power actuator81 may activate the angular position sensor 87, and the control circuit94 is programmed to store the first computed contemporaneous angulartissue-removing position of the tissue-removing element 16 as thereference angular tissue-removing position. In another example, the userinterface (e.g., display) 96 may be configured to allow the user toinstruct the control circuit 94 when to store a computed contemporaneousangular tissue-removing position of the tissue-removing element 16 asthe initial or reference angular tissue-removing position. For example,the display 96 may be a touchscreen that includes a graphical image (notshown) for allowing the user to select when to store a computedcontemporaneous angular tissue-removing position of the tissue-removingelement 16 as the reference angular tissue-removing position. In yetanother example, upon the first deployment of the tissue-removingelement 16 and activation of the driveshaft motor 30 (such as by slidingthe actuator 40 proximally), the control circuit 94 may compute andstore the contemporaneous angular tissue-removing position of thetissue-removing element 16 as the initial angular tissue-removingposition. Other ways of setting and storing the initial angulartissue-removing position of the tissue-removing element 16 do not departfrom the scope of the present invention.

After computing the reference angular position of the tissue-removingelement 16, the control circuit 94 may be programmed to communicate tothe user that the tissue-removing element 16 is positioned at 0 degrees.For example, the display 96 (e.g., an LCD display or other display) mayread “0°.” With the tissue-removing element 16 in the initial orreference angular tissue-removing position, the user may deploy thetissue-removing element 16 (such as in the manner set forth above) andwith driveshaft motor 30 rotating the tissue-removing element, the usermay make an initial “tissue-removing pass” through the stenotic lesion Tby moving the catheter body 12 distally through the body lumen BL, suchthat the tissue-removing element cuts the stenotic lesion at the initialangular location within the body lumen BL.

During the tissue-removing pass, there may be a tendency for thecatheter body 12 to rotate or become angularly displaced during atissue-removing pass because the distal end 12 b tends to travel along apath of least resistance in the body lumen BL. This tendency of thedistal end 12 b of the catheter body 12 to travel along a path of leastresistance may be referred to as “guttering,” when the tissue-removingelement 16 deviates from its angular tissue-removing position. In oneexample, the control circuit 94 may be configured (e.g., programmed) tocontinue to receive signals from the angular-displacement sensor 87 andcompute and display the angular displacement of the tissue-removingelement within the body lumen BL. Accordingly, as the user is moving thecatheter body 12 distally, the user can observe the angulartissue-removing position, which corresponds to the angular position ofthe “tissue-removing pass” within the body lumen BL. In one example, thecontrol circuit 94 may be programmed (i.e., configured) to inhibit powerfrom being supplied to the angular-positioning motor 60 when thetissue-removing element 16 is deployed, thereby inhibiting the user fromadjusting the angular tissue-removing position of the tissue-removingelement during a tissue-removing pass. Thus, if the user is notifiedthat the tissue-removing element 16 has deviated from the desiredangular location, the user can store the tissue-removing element 16,move the catheter body 12 proximally, and then attempt to make anothertissue-removing pass in an attempt to avoid guttering. Alternatively,where the control circuit 94 is not programmed to inhibit power frombeing supplied to the angular-positioning motor 60 when thetissue-removing element 16 is deployed, the user may make adjustments tothe angular tissue-removing position, such as by using the actuator 82,to maintain the tissue-removing element 16 at the desired angulartissue-removing position during a tissue-removing pass. In anotherexample, the control circuit 94 may be configured (e.g., programmed) toindicate to the user that the tissue-removing element 16 has deviatedfrom the desired angular location within the body lumen (i.e., deviateda selected threshold magnitude, such as 20 degrees or 15 degrees or 10degrees or 5 degrees). For example, the control circuit 94 may beconfigured (i.e., programmed) to flash the read-out on the display 96 oractivate another audio or visual indicator, such as an LED on thehandle.

After making the initial tissue-removing pass, the tissue-removingelement 16 may be moved to its non-deployed position (such as in amanner described above), and the catheter body 12 may be movedproximally, toward the proximal end of the target site within the bodylumen BL. The user may check the lesion T under fluorescence or otherimaging means to make a determination of the desired angular location ofthe next tissue-removing pass through the lesion. The user may thenadjust the angular tissue-removing position of the tissue-removingelement 16 by using the actuator 82, and then deploy the tissue-removingelement and move the catheter body 12 distally to make the desiredsecond tissue-removing pass. After making the second tissue-removingpass, the above steps of i) storing the tissue-removing element 16, ii)moving the catheter proximally to a proximal location of the body lesionT, iii) checking the lesion under fluorescence to make a determinationof the next desired tissue-removing pass through the lesion, iv)adjusting the angular tissue-removing position of the tissue-removingelement to a desired position, and v) making an additional“tissue-removing pass” through the lesion, are repeated a desired numberof times. The desired angular tissue-removing position of thetissue-removing element 16 may be made relative to the initial referenceangular position of the first tissue-removing pass. Alternatively, thecontrol circuit 94 may be configured to allow the user to selectivelychange the stored reference angular position used for subsequenttissue-removing passes. For example, after making the secondtissue-removing pass, the user may choose to change the referenceangular tissue-removing position for the third tissue-removing pass tobe the angular location of the second tissue-removing pass, as opposedto the angular location of the first tissue-removing pass.

As an example, as shown schematically in FIG. 7, the user may desire tomake a second tissue-removing pass at a peripheral portion of the bodylumen BL that is offset about 30 degrees clockwise from the initialtissue-removing pass. Accordingly, the user may depress the right sideof the toggle actuator 82 to activate the prime mover 60 and clockwiserotation of the apposition member 52, thus adjusting the angulartissue-removing position of the tissue-removing element 16. As the userholds down the right side of the toggle actuator 82 (alternatively, theright side of the toggle may remain depressed) and the apposition member52 and first (distal) longitudinal body portion 46 rotates clockwise,the user observes the readout on the display 96, which indicates themagnitude and direction of the angular displacement of thetissue-removing position of the tissue-removing element 16. For example,a “+” indicates that the angular displacement of the angulartissue-removing position of the tissue-removing element 16 is in theclockwise direction, and a “−” indicates that the angulartissue-removing displacement is in the counterclockwise direction. Whenthe display 96 reads “+30°” or some other readout corresponding to thedesired angular displacement, the user disengages the right side of thetoggle actuator 82 (alternatively, the user moves the toggle actuator toits center “off” position), so that the angular-positioning motor 60deactivates and ceases rotation of the apposition member 52. Next, thetissue-removing element 16 is deployed, such that the tissue-removingelement 16 engages a peripheral portion of the body lumen BL that isabout 30 degrees offset, in the clockwise direction, from the peripheralportion of the body lumen of the first tissue-removing pass, and theuser makes the second tissue-removing pass. Subsequent tissue-removingpasses may be made in the same fashion.

As disclosed above, in other embodiments the catheter 12 includes theangular-positioning mechanism 60, but does not include anangular-displacement sensor 87. Instead, the user may determine theangular tissue-removing position of the tissue-removing element 16solely through fluorescence or other imaging means. This catheter 12 hasthe benefit of allowing the user to automatically (i.e., non-manually)adjust the angular tissue-removing position of the tissue-removingelement 16. Moreover, as shown in FIG. 15, because theangular-positioning mechanism 60 (e.g., the angular-positioning motor)is within the first three-quarter length L3 of the catheter body 12(e.g., adjacent the apposition member), the torsional load applied bythe angular-positioning mechanism is not applied along the full length Lof the catheter body 12, thereby making it more likely that thetorsional force will be imparted substantially entirely along the lengthof the first (distal) longitudinal body portion 46 (i.e., rotation ofthe first (distal) longitudinal body portion, and thus the appositionmember, is substantially commensurate with rotation of the prime mover),rather than a portion or all of the torsional load being stored withinthe first (distal) longitudinal body portion (known as “lag”) andpossibly released at a later time (known as “whip”). For example, wherethe angular-positioning motor 60 and the first (distal) longitudinalbody portion 46 have a 1:1 ratio (i.e., 1 revolution of the motor equals1 revolution of the first (distal) longitudinal body portion and theapposition member) torsional load, it may be more likely that rotationalof motor degrees imparts 30 degrees of rotation to both the first(distal) longitudinal body portion and the apposition member 52 aboutthe rotational axis A2 than if the torsional load was applied at theproximal end 12 a of the catheter body 12.

As also disclosed above, in other embodiments the catheter 10 includesthe angular-displacement sensor 87, but does not include theangular-positioning mechanism 60. In such an embodiment, the angulartissue-removing position of the tissue-removing element 87 may beadjusted in the body lumen BL in a conventional manner, such as byrotating or torqueing the proximal end 12 a of the catheter body 12outside the body of the patient. The user receives feedback as to theangular tissue-removing position of the tissue-removing element 16through the display 96 or in other communication means, such as otheraudio, visual, or tactile ways. The catheter 10 including theangular-displacement sensor 87 has the benefit of facilitating moreaccurate and precise tissue removal because the user has the ability toreceive real-time feedback regarding the angular tissue-removingposition of the tissue-removing element 16 as the catheter is removingtissue from the body lumen BL. For example, as described above, the usermay be able to determine if the distal end 12 b of the catheter body 12is “guttering” and then make necessary adjustments to the catheter 10,as described above.

In another embodiment, the control circuit 94 (or another controlcircuit) of the catheter 10 may be electrically connected to (i.e., incommunication with) both the angular-positioning motor 60, forcontrolling operation of the motor, and the angular-displacement sensor87, for receiving feedback as to the angular tissue-removing position ofthe tissue-removing element 16. Accordingly, as opposed to the firstembodiment where the user directly controls the operation of theangular-positioning motor 60, in this embodiment the user inputs thedesired (i.e., inputted) angular tissue-removing position of thetissue-removing element 16 to the control circuit 94, and the controlcircuit controls the angular-positioning motor to move thetissue-removing element 16 to the desired angular tissue-removingposition. Unless otherwise indicated, the present embodiment of thecatheter is identical to the first embodiment, with like componentsbeing indicated by corresponding reference numerals, and the sameteachings set forth with respect to the first embodiment apply equallyto the present embodiment.

FIG. 16 illustrates an exemplary block diagram of the presentembodiment, showing electrical components of the catheter 10 incommunication with the control circuit 94. In this example, the controlcircuit 94 receives respective input signals from the followingcomponents: the power source 21 for regulating electrical power to theangular-positioning motor 60; the angular-displacement sensor 87 todetermine the contemporaneous angular tissue-removing position of thetissue-removing element 16; and a user input 98 for allowing a user toinput the desired angular tissue-removing position of thetissue-removing element to the control circuit 94. The power source 21may be the same power source electrically connected to the driveshaftmotor 30 (e.g., a battery in the handle), or a different power source.The angular position sensor 87 may be the same as described above, suchas a gyroscope, and as illustrated in FIGS. 2 and 12. The controlcircuit 94 sends respective output signals to the following components:the contemporaneous angle display 96 for displaying the contemporaneousangular tissue-removing position of the tissue-removing element 16; thedesired angle display 104 for displaying the desired tissue-removingposition of the tissue-removing element; and an H-bridge 100 forenabling a voltage to be applied across the angular-positioning motor 60in either direction to selectively drive the motor in the clockwisedirection and the counterclockwise direction.

Referring to FIG. 17, one embodiment of a handle (or control unit),including some of the electrical components shown in FIG. 16, isgenerally indicated at 14′. Unless otherwise indicated, the presentembodiment of the handle 14′ is identical to the first handle 14, withlike components being indicated by corresponding reference numerals, andthe same teachings set forth with respect to the first embodiment applyequally to the present embodiment. Although not illustrated, the controlcircuit 94, the power source 21, the driveshaft motor 30, and theH-bridge 100 may be provided in the handle 14′. In the illustratedembodiment, the user input 98 is in the form of a touchscreen display(e.g., an LCD touchscreen) on the handle 14′. The control circuit 94 isconfigured to generate graphical icons on the user input display 98,such as an up arrow (↑) 106, a down arrow (↓) 108, and the word “ENTER”110, as illustrated, to allow the user to communicate to the controlcircuit the desired amount of rotation of the tissue-removing element 16in the body lumen BL. The control circuit 94 is configured to generategraphical image(s) 111 on the contemporaneous angle display 96, tocommunicate the contemporaneous angular tissue-removing position of thetissue-removing element 16 to the user, and graphical image(s) 112 onthe desired angle display 104, to communicate the selected desiredangular tissue-removing position to the user.

The control circuit 94 and the user input 98 are configured so that theuser touches a respective one of the up and down arrows 106, 108,respectively, generated on the display to communicate to the controlcircuit the magnitude and direction that the user desires to change theangular tissue-removing position of the tissue-removing element 16. Inthe illustrated embodiment, the up arrow 106 indicates a change inangular position in the clockwise direction, and the down arrow 108indicates a change in angular position in the counterclockwisedirection. In one embodiment, the number of discrete times the selectedarrow 106, 108 is touched and/or the amount of time the selected arrowis continuously touched, communicates a selected the magnitude to thecontrol circuit 94 to change the angular tissue-removing position of thetissue-removing element 16 in the selected direction. This magnitude isstored in the memory and the control circuit 94 changes the graphicalimage 112 on the desired angular position display 104 to reflect theadjustment. In the illustrated embodiment, a positive graphical symbol(“+”) indicates angular displacement of the tissue-removing element 16in the clockwise direction relative to a reference angular position, anda negative graphical symbol (“−”) indicates angular displacement in thecounterclockwise direction relative to a reference angular position.

When the desired angle is presented on the display 96 (as represented bythe graphical number “+30” in FIG. 17), the user may touch the “ENTER”icon to thereby instruct the control circuit 94 to move thetissue-removing element 16 to angular tissue-removing position presentedon the display 104, which is also stored in memory. The control circuit94 communicates with the angular-positioning motor 60 to adjust thetissue-removing element 16. The display 96, which may be similar oridentical to the corresponding display of the prior handle embodiment,outputs the contemporaneous angular tissue-removing position of thetissue-removing element 16, as computed by the control circuit 94 usingsignals from the angular position sensor 87. The control circuit 94 mayuse the signals from the angular position sensor 87 as feedback forpositioning the tissue-removing element. In another example, the controlcircuit 94 may be configured to adjust the angular tissue-removingposition of the tissue-removing element 16 in other ways. For example,the control circuit 94 may be configured (e.g., programmed) to supplythe angular-positioning motor 60 with a pre-selected amount of power fora pre-selected amount of time to adjust the tissue-removing element 16to the desired (i.e., inputted) angular tissue-removing position.

Because the control circuit 94 controls the angular tissue-removingposition of the tissue-removing element 16, in one or more embodimentsthe control circuit may be configured to maintain the tissue-removingelement 16 in substantially the desired (i.e., inputted) angulartissue-removing position, as the user is making a tissue-removing passin the body lumen BL. In this embodiment, the control circuit 94 usesthe signals from the angular position sensor 87 as feedback formaintaining the tissue-removing element in its selected angulartissue-removing position in the body lumen BL. This embodiment is meantto counteract the tendency of distal end 12 b of the catheter body 12 togutter during a tissue-removing pass and inhibit the tissue-removingelement 16 from deviating from the desired and selected angular positionof the tissue-removing pass.

In one embodiment, the catheter 10 may be configured to restrict orlimit the amount of rotation of the apposition member 52 and the first(distal) longitudinal body portion 46 about the rotation axis A2. Forexample, the control circuit 94 may be programmed to inhibit the userfrom rotating beyond about 360 degrees. That is, the control circuit 94may be programmed to use the signals from the angular position sensor 87as feedback and inhibit the user from increasing the angular position ofthe tissue-removing element beyond about 360 degrees from the initialreference position. The catheter 10 may also include an indicator, suchas a visual indicator (e.g., and LED), audio indicator, or tactileindicator, on the handle 14′ to communicate to the user that thetissue-removing element 16 has reached a maximum allowable angulardisplacement and further rotation of the tissue-removing element 16 inthe same direction is inhibited. Without restricting the amount ofrotation of the first (distal) longitudinal body portion 46, a guidewire(not shown) may wrap around and become tangled with the catheter body12. Moreover, the rotating the apposition member 52 and the first(distal) longitudinal body portion 46 more than 360 degrees may placeundue tension on the electrical conductors 92 (e.g., wires) connectingthe sensor 87 to the handle 14, which may damage the connections betweenthe conductors and the sensor and the handle. Other ways of restrictingrotation of the apposition member 52 and the first (distal) longitudinalbody portion 46 about the rotation axis A2 do not depart from the scopeof the present invention. In one example, the catheter 10 may include amechanical stop, such as a stop adjacent the prime mover 60, forinhibiting the prime mover from rotating more than about 360 degrees.

Although the control circuit 94 is illustrated as a single, integratedcircuit throughout the drawings and the above-described embodiments, itis understood that the control circuit may include separate, individualcontrol circuits (e.g., separate microcontrollers), each dedicated toone of the prime mover and the angular-displacement sensor.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions, products,and methods without departing from the scope of the invention, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:
 1. A tissue-removing catheter for removing tissuefrom a body lumen having a longitudinal axis, the tissue-removingcatheter comprising: a catheter body configured for insertion in thebody lumen, the catheter having a proximal end, a distal end, and alongitudinal axis extending between the proximal and distal ends,wherein at least a first longitudinal body portion of the catheter bodyis rotatable about a rotational axis extending along the length of thecatheter body; a tissue-removing element coupled to the firstlongitudinal portion of the catheter body; and an angular-displacementsensor coupled to the catheter body and configured to detect an angulardisplacement of at least said first longitudinal portion of the catheterbody relative to the rotational axis when the first longitudinal bodyportion is rotated about the rotational axis.
 2. The tissue-removingcatheter set forth in claim 1, wherein the angular-displacement sensoris coupled to the first longitudinal portion of the catheter body. 3.The tissue-removing catheter set forth in claim 2, wherein theangular-displacement sensor is configured to rotate with the firstlongitudinal body portion of the catheter body.
 4. The tissue-removingcatheter set forth in claim 1, wherein the tissue-removing element isconfigured to rotate with the first longitudinal body portion about therotational axis, wherein the angular-displacement sensor is coupled tothe first longitudinal portion of the catheter body and configured torotate with the first longitudinal body portion and the tissue-removingelement about the rotational axis.
 5. The tissue-removing catheter setforth in claim 1, wherein the angular-displacement sensor comprises agyroscope.
 6. The tissue-removing catheter set forth in claim 1, furthercomprising: at least one electrical conductor electrically connected tothe angular-displacement sensor and electrically connectable to acontrol circuit for receiving electrical signals from theangular-displacement sensor indicative of the angular displacement of atleast said first longitudinal portion of the catheter body relative tothe rotational axis when the tissue-removing element is rotated aboutthe rotational axis.
 7. The tissue-removing catheter set forth in claim6, further comprising: a control circuit connectable to the at least oneelectrical conductor electrically connected to the angular-displacementsensor, wherein the control circuit is configured to: receive electricalsignals from the angular-displacement sensor indicative of an angulardisplacement of the first longitudinal portion of the catheter bodyrelative to a reference angular position of the first longitudinalportion of the catheter body; and compute the angular displacement ofthe first longitudinal body portion using the received electricalsignals from the angular-displacement sensor.
 8. The tissue-removingcatheter set forth in claim 7, further comprising a control unitconnectable to the catheter body, the control unit comprising thecontrol circuit.
 9. The tissue-removing catheter set forth in claim 7,wherein the control unit comprises a display electrically connected tothe control circuit for displaying the computed angular displacement ofthe first longitudinal body portion.
 10. The tissue-removing catheterset forth in claim 7, wherein the catheter body includes a secondlongitudinal body portion proximal of the first longitudinal bodyportion, the first longitudinal body portion being rotatable along itslength relative to the second longitudinal body portion to adjust theangular position of the first longitudinal body portion relative to thesecond longitudinal body portion.
 11. The tissue-removing catheter setforth in claim 10, further comprising an angular-positioning mechanismoperatively connected to the first longitudinal body portion andconfigured to rotate the first longitudinal body portion along itslength and relative to the second longitudinal body portion to adjustthe angular position of the first longitudinal body portion relative tothe second longitudinal body portion.
 12. The tissue-removing catheterset forth in claim 11, wherein the angular-positioning mechanismcomprises a prime mover, the control circuit being operativelyconnectable to the prime mover for controlling operation of the primemover for imparting rotation to the apposition member relative to thesecond longitudinal body portion of the catheter body.
 13. Thetissue-removing catheter set forth in claim 12, further comprising acontrol unit connectable to the catheter body, the control unitcomprising the control circuit, wherein the control unit comprises adisplay electrically connected to the control circuit for displaying thecomputed angular displacement of the first longitudinal body portion,wherein the control unit comprises a user input electrically connectedto the control circuit for instructing the control circuit to rotate thefirst longitudinal body portion to a selected angular position relativeto the reference angular position.
 14. A tissue-removing catheter forremoving tissue from a body lumen having a longitudinal axis, thetissue-removing catheter comprising: a catheter body configured forinsertion in a body lumen of a subject, the catheter having a proximalend, a distal end, a longitudinal axis extending between the proximaland distal ends; a tissue-removing element coupled to the catheter bodyand configured to be positioned in an angular tissue-removing positionrelative to the longitudinal axis of the body lumen when the catheterbody is inserted in the body lumen, the tissue-removing element beingrotatable about a rotational axis to adjust an angular tissue-removingposition of the tissue-removing element relative to the longitudinalaxis of the body lumen when the catheter body is inserted in the bodylumen; an angular-displacement sensor generally adjacent thetissue-removing element, the angular-displacement sensor configured todetect an angular displacement of the tissue-removing element relativeto the longitudinal axis of the body lumen when the tissue-removingelement is rotated about the rotational axis.
 15. The tissue-removingcatheter set forth in claim 14, wherein the angular-displacement sensoris configured to rotate with the tissue-removing element about therotational axis.
 16. The tissue-removing catheter set forth in claim 15,wherein the angular-displacement sensor comprises a gyroscope.
 17. Thetissue-removing catheter set forth in claim 14, further comprising: atleast one electrical conductor electrically connected to theangular-displacement sensor and electrically connectable to a controlcircuit for receiving electrical signals from the angular-displacementsensor indicative of the angular displacement of the tissue-removingelement relative to the rotational axis.
 18. The tissue-removingcatheter set forth in claim 17, further comprising: a control circuitconnectable to the at least one electrical conductor electricallyconnected to the angular-displacement sensor, wherein the controlcircuit is configured to: receive electrical signals from theangular-displacement sensor indicative of an angular displacement of thetissue-removing element relative to a reference angular position of thetissue-removing element; and compute the angular displacement of thetissue-removing element using the received electrical signals from theangular-displacement sensor.
 19. The tissue-removing catheter set forthin claim 18, further comprising a control unit connectable to thecatheter body, the control unit comprising the control circuit.
 20. Thetissue-removing catheter set forth in claim 18, wherein the control unitcomprises a display electrically connected to the control circuit fordisplaying the computed angular displacement of the tissue-removingelement.
 21. The tissue-removing catheter set forth in claim 14, whereinthe catheter body includes a first longitudinal body portion and asecond longitudinal body portion proximal of the first longitudinal bodyportion, the first longitudinal body portion being rotatable along itslength relative to the second longitudinal body portion to adjust theangular position of the first longitudinal body portion relative to thesecond longitudinal body portion, wherein the tissue-removing element iscoupled to the first longitudinal body portion such that thetissue-removing element rotates with the first longitudinal bodyportion.
 22. The tissue-removing catheter set forth in claim 21, furthercomprising an angular-positioning mechanism operatively connected to thefirst longitudinal body portion and configured to rotate the firstlongitudinal body portion along its length and relative to the secondlongitudinal body portion to adjust the angular position of the firstlongitudinal body portion relative to the second longitudinal bodyportion.
 23. The tissue-removing catheter set forth in claim 22, whereinthe angular-positioning mechanism comprises a prime mover, the controlcircuit being operatively connectable to the prime mover for controllingoperation of the prime mover for imparting rotation to the firstlongitudinal body portion relative to the second longitudinal bodyportion.
 24. The tissue-removing catheter set forth in claim 23, furthercomprising a control unit connectable to the catheter body, the controlunit comprising the control circuit, wherein the control unit comprisesa display electrically connected to the control circuit for displayingthe computed angular displacement of the first longitudinal bodyportion, wherein the control unit comprises a user input electricallyconnected to the control circuit for instructing the control circuit torotate the first longitudinal body portion to a selected angularposition relative to a reference angular position.